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Endochondral ossification is responsible for development of most bones including long and short bones, [4] the bones of the axial (ribs and vertebrae) and the appendicular skeleton (e.g. upper and lower limbs), [5] the bones of the skull base (including the ethmoid and sphenoid bones) [6] and the medial end of the clavicle. [7]
The following bones develop in humans via Intramembranous ossification: [3] Flat bones of the face; Most of the bones of the skull; Clavicles; Other bone that formed by intramembranous ossification are: cortices of tubular and flat bones as well as the calvaria, upper facial bones, tympanic temporal bone, vomer, and medial pterygoid process. [4]
The formation of bone is called ossification. During the fetal stage of development this occurs by two processes: intramembranous ossification and endochondral ossification. [42] Intramembranous ossification involves the formation of bone from connective tissue whereas endochondral ossification involves the formation of bone from cartilage.
The three main mechanisms by which osteoporosis develops are an inadequate peak bone mass (the skeleton develops insufficient mass and strength during growth), excessive bone resorption, and inadequate formation of new bone during remodeling, likely due to mesenchymal stem cells biasing away from the osteoblast and toward the marrow adipocyte ...
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone. [5] [6] It is believed to be the fourth leading cause of disability in the world, affecting 1 in 7 adults in the United States alone. [7]
The PDL is a part of the periodontium that provides for the attachment of the teeth to the surrounding alveolar bone by way of the cementum. PDL fibres also provide a role in load transfer between the teeth and alveolar bone. (PDL fibers absorb and transmit forces between teeth and alveolar bone.
OPN at bone surfaces is located in a thin organic layer, the so-called lamina limitans. [72] The organic part of bone is about 20% of the dry weight, and counts in, other than osteopontin, collagen type I, osteocalcin, osteonectin, and alkaline phosphatase. Collagen type I counts for 90% of the protein mass.
The skeleton consists of very lightweight bones. They have large air-filled cavities (called pneumatic cavities) which connect with the respiratory system. [77] The skull bones in adults are fused and do not show cranial sutures. [78] The orbital cavities that house the eyeballs are large and separated from each other by a bony septum (partition).